CAUTIONARY NOTE: This Outlook is based on the assumption that weather beyond the
period of the current U.S. Weather Bureau 30-day Outlook will be normal. Therefore, the
forecasts given below cannot be viewed with the same degree of confidence as those in the
"Insect and Disease Summary" usually released twice each month by this Station.
Each pest has more or less regular periods of increase and decrease throughout the
year. Weather conditions (temperature, rain, humidity) may affect populations directly,
or indirectly through effects on predators, parasites and tree growth. Departures from
the average population level may be caused by conditions that occurred months before.
Other fluctuations may reflect recent weather changes. The latter influences can be
forecast only to the extent that weather forecasts are available.
RECENT SITUATION APRIL THROUGH JUNE 1969
Rust mite was the only citrus pest of wide concern; however, several other pests
attained notable high populations during the period.
Rust mite was above normal abundance April through June and population in May was
the highest in 18 years for that month. Moderate or heavy infestations occurred in 57%
of groves.
Citrus red mite and Texas citrus mite were below normal abundance. Neither had
attained a high level by the end of June when the peak population usually occurs. Less
than 31% of groves harbored moderate or heavy infestations of either species. Citrus
red mite was at the lowest June level in 18 years.
Six-spotted mites occurred mid-April through mid-June at the low average level of
recent years. About 2% of groves developed moderate to heavy infestations.
Most scale species were unimportant. Glover scale was the most numerous and at-
tained a high level in late June although population was below normal for the period.
Only 15% of groves developed moderate or heavy infestations. Purple scale remained
below normal and at low to moderate level. Chaff scale also remained below normal and
low. Yellow scale held to a normal moderate population throughout the period. Black
scale was much less abundant than average until mid-May, then rapidly increased to the
normal high level by the end of June, when moderate to heavy infestations were found
in 59% of groves.
Green scale, although of little concern, was more abundant than in the prior 18 years
of record. Moderate to heavy infestations occurred in 5% of groves. Snow scale con-
tinued its gradual increase and developed moderate to heavy infestations in 7% of groves.
Aphids were more numerous at the late April peak of population than at any time in
18 years of observations. In April, 21% of groves had moderate or heavy infestations
with green citrus aphid predominating.
Whiteflies were at normally low levels in April. They increased rapidly in May and
June and nearly reached the 18 year high level. This was true for larval, pupal and adult
forms.
Mealybug population changed from extremely low in late April to abnormally high in
late June. Moderate to heavy infestations developed in 40% of groves.
Weather was quite normal during the period. The abnormally cool weather of the
preceding March undoubtedly influenced pest populations.
GENERAL FORECAST JUNE THROUGH SEPTEMBER 1969
Rust mite population is expected to continue at abnormally high level until mid-
August; then decrease to low level in September.
Citrus red mite and Texas citrus mite will occur as scattered infestations in a few
groves but generally will be below normal and unimportant.
Black scale will be abundant through July, then decrease. Young crawlers are ex-
pected to be numerous late in August but most of these will die.
Glover scale, purple scale, yellow scale and chaff scale will be present in a majority
of groves although less than 10% are likely to have important infestations. Decrease to
low level is expected August through September.
Snow scale infestations are likely to be found in new areas. Delineation of infested
areas is an aid to effective control.
Whiteflies are expected to be above normal abundance and in the high range through
July, then decrease to low level.
Mealybugs will continue high through July, then gradually decrease to low level in
August and September.
Sooty mold will be more abundant than a er Afe |hti ns of aphids, black
scale, whitefly and mealybug occurred. U ILLI I I